water
Article Hydrogeochemical Characteristics and Assessment of Drinking Water Quality in the Urban Area of Zamora, Mexico
Claudia Alejandra Reyes-Toscano 1, Ruth Alfaro-Cuevas-Villanueva 2,*, Raúl Cortés-Martínez 3 , Ofelia Morton-Bermea 4 , Elizabeth Hernández-Álvarez 4, Otoniel Buenrostro-Delgado 2 and Jorge Alejandro Ávila-Olivera 2
1 Maestría en Ciencias en Ingeniería Ambiental, Universidad Michoacana de San Nicolás de Hidalgo, Edif. M, C.U., Morelia 58030, Mexico; [email protected] 2 Instituto de Investigaciones en Ciencias de la Tierra, Universidad Michoacana de San Nicolás de Hidalgo, Edificio U3, C.U., Morelia 58030, Mexico; [email protected] (O.B.-D.); [email protected] (J.A.Á.-O.) 3 Facultad de Químico Farmacobiología, Universidad Michoacana de San Nicolás de Hidalgo, Tzintzuntan 173, Colonia Matamoros, Morelia 58240, Mexico; [email protected] 4 Instituto de Geofísica, Universidad Nacional Autónoma de México. Circuito Exterior S/N, Ciudad Universitaria, Mexico D.F. 04510, Mexico; omorton@geofisica.unam.mx (O.M.-B.); [email protected] (E.H.-Á.) * Correspondence: [email protected]; Tel.: +52-443-340-5079
Received: 31 December 2019; Accepted: 4 February 2020; Published: 17 February 2020
Abstract: This work assessed the groundwater hydrogeochemistry and the drinking water quality of 10 wells supplying the urban area of Zamora, Michoacán, Mexico. Two sampling campaigns were conducted in May 2018 (dry season) and November 2018 (wet season) to describe the chemistry of the water and its interaction with the rock. Physical and chemical constituents (temperature, pH, electrical conductivity, color, turbidity, solids, total hardness, total alkalinity, chemical and biochemical oxygen 2+ 2+ + + 2 3 2 demands), major components (Ca , Mg , Na ,K , SO4 −, PO4 −, HCO3−, CO3 −, Cl−, N-NO3−, and N-NH3), as well as trace elements (As, Fe, Mn, Ba, Al, Sb, Co, V, Cu, Cd, Cr, Ni, Zn, Tl, Pb) were analyzed. Results showed groundwater with a slight tendency to alkalinity. The hydrogeochemical 2+ facies observed are Ca -HCO3− in all sites. Hydrochemical diagrams indicate immature, cold, non-saline, and uncontaminated water with short residence time. Water–rock interaction predominates. The water in the study area is appropriate for drinking use according to Mexican and international regulations with an excellent quality in 7 wells and good in the other 3.
Keywords: groundwater; water chemistry; hydrogeochemistry; hydrogeochemical facies; drinking water; Zamora; Mexico; water quality index
1. Introduction Groundwater is one of the most valuable natural resources, playing a fundamental role in human health and wellness, socio-economic development, and ecosystem functioning. Moreover, it is widely used for various domestic, industrial, and irrigation activities [1]. In recent decades, groundwater pollution has become one of the most severe problems in the world, as water can be affected from natural sources or from numerous types of human activities, which can result in poor drinking water quality, water supply losses, high cleaning costs and potential health problems [2].
Water 2020, 12, 556; doi:10.3390/w12020556 www.mdpi.com/journal/water Water 2020, 12, 556 2 of 26
Groundwater quality is based on the behavior of physical and chemical parameters that are influenced by geological formations, atmospheric precipitation, inland surface water, and geochemical processes as they are in contact with the rock and the various anthropogenic activities [3]. Water chemistry provides valuable information to determine the origin, transit time, flow patterns and water regimes, geological structure, and mineralogy of aquifers, as well as hydrogeochemical processes. Specific water quality is required to meet both domestic and irrigation needs. Their monitoring and evaluation are essential to design preventive measures on human health, animal life, and vegetation [4]. Geographic Information Systems (GIS) play an important role in understanding and managing water resources and in the study of their pollution, which together with hydrogeochemical analysis, can be important tools in the exploitation of this natural resource [5]. Zamora, Michoacán has an aquifer consisting of basaltic, pyroclastic, alluvial materials, and lake deposits [6]. This city uses this resource to supply drinking water, obtaining it by pumping into wells. The objective of this research was to carry out a geochemical study of the groundwater used as drinking water in Zamora, Mexico, by analyzing physicochemical parameters, major ions, and trace elements, together with chemical speciation, hydrogeochemical relationships, and spatial distribution maps.
2. Materials and Methods
2.1. Location of the Study Area The city of Zamora belongs to the Bajío Region in the State of Michoacán, Mexico. It is located between the parallels 19◦560 and 20◦070 N, and meridians 102◦070 and 102◦250 W, at an altitude of 1580 m. It borders North with Ixtlan and Ecuandureo municipalities; to the East with the municipalities of Ecuandureo, Tlazazalca, and Tangancicuaro; to the South with the municipalities of Tangancicuaro and Jacona; to the West with the municipalities of Jacona, Tangamandapio, Chavinda, and Ixtlan. It has an area of 335.55 km2, covering 0.56% of the state. It has a total population of 186,102 [7]. The weather is warm-subhumid with summer rains. It has an annual rainfall between 700 and 1000 mm and temperatures between 16 and 22 ◦C[7]. It is the third most populous city in the state. Zamora is one of the most important producers of blackberry and strawberry in the country; it has processing and packing companies, which export these products. Its geographical location sets the city as an important commercial and economic link between the capital of the state (Morelia) and the city of Guadalajara (the third most important in the country) [7]. Zamora is in the Sub-basin of Duero River, belonging to the Lerma Santiago hydrological region [8]. Figure1 shows the location of the studied area and the selected sampling wells. Water 2020, 12, 556 3 of 26 Water 2020, 12, x FOR PEER REVIEW 3 of 25
Figure 1. Location of the sampling sites in the urban area of Zamora, Mexico. Figure 1. Location of the sampling sites in the urban area of Zamora, Mexico. 2.2. Geology and Hydrogeology 2.2. Geology and Hydrogeology The studied area is located in the sub-province of “Area of TectonicPits”, located at the northwestern partThe of Michoac studiedá n area state is (Figure located2 ), in which the sub is- characterizedprovince of “Area by the of alignment Tectonic Pits” of its, located basins in at an the East-Westnorthwestern direction. part of Michoacán state (Figure 2), which is characterized by the alignment of its basinsThis in an region East has-West constant direction. volcanic activity, reflected by many volcanic systems and extrusive rocks, madeThis up mainlyregion ofhas basaltic constant and volcanic andesitic activity, rocks [6 reflected]. by many volcanic systems and extrusive rocks,The made altitude up mainly ranges of from basaltic 1530 and to1600 andesitic m, located rocks in[6]. an old lake basin, thicker than 300 m; to the north,The there altitude are alignments ranges from due 1530 to to the 1600 eff ortsm, located exerted in on an theold extrusivelake basin, igneous thicker rocksthan 300 of andesiticm; to the compositionnorth, there thatare a constitutelignments the due basement to the efforts of the exertedregion [ 6 on]. the extrusive igneous rocks of andesitic compositionThe mountain that constitute range surrounding the basement the of Zamora the region Valley [6]. contains Quaternary basalts, underlying lowerThe permeability mountain range volcanic surrounding rocks. They the have Zamora high Valley permeability contains andQuaternary infiltration basalts, capacity underlying due to theirlower vesicular permeability texture volcani andc fracturing; rocks. They therefore, have high they permeability are excellent and recharge infiltration receptors capacity and due constitute to their permeablevesicular texture aquifers and in the fracturing; subsoil of therefore, the southern they portion are excellent of the valley, recharge where receptors alluvial and deposits constitute cover them.permeable In contrast, aquifers Tertiaryin the subsoil basalts of have the southern lower infiltration portion of and the permeabilityvalley, where capacity,alluvial deposits because cover their structurethem. In contrast, is massive Tertiary and poorly basalts fractured. have lower They infiltration have a staggered and permeability pattern because capacity, of tectonism because their and constitutestructure is the massive geohydrological and poorly basement fractured. of They the aquifer.have a staggered The primary pattern aquifer because in the of valleytectonism consists and ofconstitute basaltic, the pyroclastic, geohydrological alluvial basem materials,ent of and the lakeaquifer. deposits; The primary the first aquifer three arein the the valley most permeableconsists of elements;basaltic, pyroclastic, the others are alluvial aquitards materials, of medium and lake to low deposits; permeability. the first Its three thickness are the increases most permeable from the edgeselements; towards the others the center are aquitards of the valley, of medium it is inferiorly to low limitedpermeability. by old Its lake thickness deposits, increases and in the from lower the portionsedges towards of the valley,the center it is of semi-confined the valley, it by is recentinferiorly lake limited deposits by [ 6old] (Table lake 1deposits,). and in the lower portions of the valley, it is semi-confined by recent lake deposits [6] (Table 1).
Water 2020, 12, 556 4 of 26 Water 2020, 12, x FOR PEER REVIEW 4 of 25
Figure 2. Geology in the urban area of Zamora, Mexico. Figure 2. Geology in the urban area of Zamora, Mexico. Table 1. Lithological column of Zamora Municipality, Michoacán. Table 1. Lithological column of Zamora Municipality, Michoacán. Layer Depth (m) Lithological Description Layer Depth (m) Lithological Description 1 1.5 Clasts and rock fragments with scoria and clay sands, without saturation. 1 1.5 Clasts and rock fragments with scoria and clay sands, without saturation. Deposits with swampy materials, with silts and clays, interacting with siliceous 2 17 Deposits with swampy materials, with silts and clays, interacting with sediments and fine granulometry clastic materials without saturation. 2 17 siliceous sediments and fine granulometry clastic materials without Clastic material, rock pieces, scoria, and cineritic material, with sandy-clay sediments, 3 45 saturation. Clastic material, rock pieces, scoriaand low, and saturation. cineritic material, with sandy-clay 3 45 4 150 Extrusive rocks of fracturedsediments, basaltic and composition,low saturation. with saturation possibility. 4 150 ExtrusiveBasic compositionrocks of fractured extrusive basaltic igneous composition, rocks, compact with saturation to slightly possibility. fractured, 5 250 Basic composition extrusive igneous rocks, compact to slightly fractured, with 5 250 with saturation traces. saturation traces. Extrusive igneous rocks of basaltic composition, fractured, altered with volcanic gaps, 6 >250 Extrusive igneous rocks of basaltic composition, fractured, altered with 6 >250 with saturation possibility. volcanic gaps, with saturation possibility.
2.3. Sampling 2.3. Sampling Ten representative sampling sites of the studied area were selected (Table2), located in strategic Ten representative sampling sites of the studied area were selected (Table 2), located in strategic areas such as growing areas, wells adjacent to the Duero River, sites with high population index, areas such as growing areas, wells adjacent to the Duero River, sites with high population index, and and areas with poor or no health infrastructure. areas with poor or no health infrastructure. Two sampling campaigns were performed in May (dry season) and November (end of the rainy Two sampling campaigns were performed in May (dry season) and November (end of the rainy season) 2018. season) 2018. Samples were taken to analyze physicochemical parameters, major ions, and trace elements. Samples were taken to analyze physicochemical parameters, major ions, and trace elements. The sampling for physicochemical parameters was carried out in 2 L polyethylene bottles (HDPE) The sampling for physicochemical parameters was carried out in 2 L polyethylene bottles (HDPE) filled to minimize the presence of air to avoid chemical changes. filled to minimize the presence of air to avoid chemical changes. The trace elements samples were taken in 125 mL HDPE containers previously decontaminated The trace elements samples were taken in 125 mL HDPE containers previously decontaminated with HNO3 and filled with deionized water [9]. In the field, one bottle was used as a control draining with HNO3 and filled with deionized water [9]. In the field, one bottle was used as a control draining and refilling it with deionized water to obtain data concerning possible pollutants from sources different and refilling it with deionized water to obtain data concerning possible pollutants from sources from water. A second bottle was emptied and filled with the sample. These containers were preserved different from water. A second bottle was emptied and filled with the sample. These containers were with ultrapure HNO3 [9,10]. preserved with ultrapure HNO3 [9,10]. All samples were kept in refrigeration (4 C) until the analysis indicated in the regulation. All samples were kept in refrigeration (4 ◦°C) until the analysis indicated in the regulation.
Water 2020, 12, 556 5 of 26
Table 2. Location and depth of the studied wells in the urban area of Zamora, Michoacán.
Site Coordinates Depth (m)
P1 19◦58040.500 N 102◦17043.200 W 55 P2 19◦58038.500 N 102◦17010.700 W 40 P3 19◦58044.700 N 102◦17004.400 W 60 P4 19◦58033.300 N 102◦16044.400 W 90 P5 19◦58023.200 N 102◦16019.600 W 150 P6 19◦58059.300 N 102◦16044.000 W 150 P7 19◦59038.400 N 102◦18010.700 W 180 P8 20◦00014.700 N 102◦17028.000 W 120 P9 19◦59012.200 N 102◦16033.800 W 140 P10 19◦59024.000 N 102◦15002.500 W 130
2.4. Measurement Techniques Temperature (T), pH and electrical conductivity were measured in situ, and total hardness, 2+ 2+ + + 2 2 total alkalinity, Ca , Mg , Na ,K , Cl−, SO4 −, N-NH3, HCO3−, CO3 −, and trace elements (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Tl, V, Zn) were determined in the laboratory. Electrical conductivity and pH were measured in situ with a potentiometer (Thermo Scientific Orion Star A320), and the temperature was measured with an immersion thermometer [10]. Analytical techniques of potentiometry, volumetry, and atomic absorption spectrometry were used in the determination of the physicochemical parameters in the laboratory, following the recommendations of the Mexican regulations and the Standard Methods [10]. The trace elements analysis was performed by inductively coupled plasma mass spectrometry technique (ICP-MS). The quality of the chemical data was assessed by calculating ion balances (IB). All IB were found below 10%; therefore, all samples were considered in the calculations of this work. Geochemical methods were used to establish the processes controlling the groundwater chemistry: chemical speciation of trace elements was calculated, and Piper, Giggenbach, Schöller, Gibbs, and binary diagrams were built, in addition to Chloro Alkaline Indices.
2.5. Water Quality Index The Groundwater Quality Index used in this work was developed by Brown et al. [11]. The method is used for the evaluation of groundwater quality worldwide due to the ability to express information on water quality. Moreover, it is one of the most effective tools for the evaluation and management of groundwater quality [12]. The procedure takes place in three stages. In the first stage an individual weight (wi) between 2 2+ 1 and 5 is assigned to 13 parameters (pH, Total Dissolved Solids (TDS), Cl−, SO4 −, HCO3−, Ca , 2+ + + Mg , Na ,K , Total Hardness, F−, NO3− and N-NH3) depending on its importance in the evaluation of water quality [3]. In the second stage, the relative weight (Wi) of each parameter is calculated using Equation (1):
wi Wi = Pn (1) i=1 wi where Wi is the relative weight of each parameter, wi is the weight of each parameter, and n is the number of parameters. Table3 indicates the values of wi and Wi.
Table 3. Weights and relative weights of the parameters to evaluate the water quality index.
Parameter Weight (wi) Relative Weight (Wi) pH 4 0.089 TDS 5 0.111 Cl− 3 0.067 Water 2020, 12, 556 6 of 26
Table 3. Cont.
Parameter Weight (wi) Relative Weight (Wi) 2 SO4 − 5 0.111 Na+ 3 0.067 K+ 2 0.044 HCO3− 1 0.022 Ca2+ 3 0.067 Mg2+ 3 0.067 NO3− 5 0.111 Hardness 4 0.089 F− 5 0.111 N-NH3 2 0.044 TOTAL 45 1
In the third stage, the quality rating for each parameter is calculated from Equation (2): ! Ci qi = 100 (2) Si where qi is the quality rating, Ci is the concentration of each chemical parameter, Si is the concentration of the standards established by the Official Mexican Standard [13] and by World Health Organization (WHO). Table4 shows the maximum permissible limits of Mexican and international regulations. In the fourth stage, the sub-index of ith parameter (SIi) is calculated for each parameter using Equation (3):
SIi= Wi qi (3) where SIi is the sub-index of the ith parameter, qi is the quality rating, and Wi is the relative weight.
Table 4. Maximum permissible limits of Mexican and international regulations. Concentrations are expressed in mg/L.
Parameter Mexican Regulation WHO Regulation pH 6.5–8.5 6.5–8.5 TDS 1000 1000 Cl− 250 250 2 SO4 − 400 250 Na+ 200 200 K+ - 12 HCO3− - 120 Ca2+ - 75 Mg2+ - 50 NO3− 10 45 Hardness 500 500 3 PO4 − - 10 N-NH3 0.5 1.5
Finally, Water Quality Index (WQI) is obtained from Equation (4): X WQI = Si (4)
WQI values are classified into five categories (Table5): excellent, good, fair, poor and unacceptable for human use [12]. Water 2020, 12, 556 7 of 26
Table 5. Classification of the Water Quality Index.
WQI Water Quality <50 Excellent 50–100 Good 100–200 Fair 200–300 Poor >300 Unacceptable
3. Results and Discussion
3.1. In Situ Parameters
The water temperature showed values between 21 ◦C and 37 ◦C. Although two wells exceeded 30 ◦C, the water in this area is not considered to be thermal. The highest temperatures were observed in May in all wells within the spring season. pH values ranged from 6.73 to 8.45, showing an alkaline behavior due to water mineralization, probably coming from the salt content in the rock surrounding the aquifer. The highest values at all sites were observed in May, which corresponds to the end of the dry season. It can be assumed that in this season the concentration of salts that provide alkalinity to water was higher than that observed in November, which corresponds to the last month of the rainy season, in which the recharge of the aquifer allowed the dissolution of the ions, which can be confirmed with the reported concentrations, in particular, the presence of carbonates and bicarbonates. The electrical conductivity shows the presence of dissolved salts in the water that are generally incorporated into the water from geochemical processes such as ion exchange, evaporation, silicate weathering, and the solubilization process that take place within the aquifers [14]. In this study, values between 311 and 957 µS/cm were observed. Most sites had the highest values in spring (May). Electrical conductivity is a parameter directly related to the presence of ions in dissolution, so the presence of dissolved salts can be observed in all sites. Table6 shows the temperature, pH, and electrical conductivity values observed in this study.
Table 6. Results of the parameters measured in situ in two sampling campaigns.
Temperature Electrical Conductivity Site Sampling Campaign pH (◦C) (µS/cm) May 18 24 8 461 P1 Nov 18 21 7.67 498.6 May 18 25 7.6 608 P2 Nov 18 23 7.52 743.9 May 18 26 7.98 820 P3 Nov 18 23 6.73 957.6 May 18 31 8.31 428 P4 Nov 18 27 7.63 495.3 May 18 28 8.27 479 P5 Nov 18 21 7.33 511.4 May 18 37 8.45 394 P6 Nov 18 24 7.85 386.5 May 18 28 8.34 389 P7 Nov 18 26 7.69 396.2 May 18 29 8.08 412 P8 Nov 18 24 7.43 418.2 Water 2020, 12, 556 8 of 26
Table 6. Cont.
Temperature Electrical Conductivity Site Sampling Campaign pH (◦C) (µS/cm) May 18 29 8.11 348 P9 Nov 18 27 7.67 335.6 May 18 27 8.32 311 P10 Nov 18 22 7.78 343.6 NOM-127-SSA1-1994 - - 6.5–8.5 - USEPA - - 6.5–8.5 -
3.2. Physicochemical Parameters The turbidity and color values were under the limit recommended by the Mexican regulations (5 UTN and 20 Pt-Co units, respectively); however, the turbidity exceeded the United States Environmental Protection Agency (USEPA) recommendation for drinking water at all sites (1 UTN). Turbidity values ranged from 1.35 to 4.6 UTN, while color was observed in a range of 5 to 10 Pt-Co units. Turbidity values were mostly higher at the end of the rainy season (November), probably due to the resuspension of solids during the aquifer recharge. The color showed no differences between both seasons. Settable, suspended, dissolved, and total solids were analyzed, showing a more significant contribution of dissolved solids over the concentration of total solids. TDS represent different types of dissolved minerals. These vary considerably in different geological regions due to differences in mineral solubilities [15]. Mexican regulation recommends a maximum permissible limit in drinking water of dissolved solids of 1000 mg/L while the USEPA recommendation is 500 mg/L for this parameter. P3 site was the only one that exceeded the USEPA recommendation in both sampling campaigns. The total solids concentration ranged between 254 mg/L and 646 mg/L. Most sites showed the highest concentrations of dissolved and total solids during the dry season. A direct relationship between the concentration of dissolved solids and the value of the electrical conductivity of the water can be observed. Sites P2 and P3 show the highest presence of both parameters, while sites P9 and P10 have the lowest values, indicating the lowest presence of dissolved salts. Alkalinity represents the presence of carbonate and bicarbonate salts in water [5]. This parameter has a direct relationship with hardness, which is usually mainly due to the presence of calcium and magnesium expressed as CaCO3. Other ions, such as iron or manganese, also contribute to this parameter [16,17]. The hardness value depends on pH and alkalinity values since the pH determines the dissolution capacity of the minerals in the water. In this study, the relationship between these three parameters can be seen, showing a similar behavior between hardness and alkalinity, so a carbonated type of hardness can be inferred. This relationship allows us to infer the majority presence of carbonate and bicarbonate salts mainly of calcium and, in a smaller concentration, magnesium, iron, and manganese in this studied area. The total hardness and alkalinity showed the lower concentrations slightly in the rainy season, probably due to the dilution. The BOD5 values observed indicate that the water does not receive representative organic contamination. It was important to determine this parameter because some of the wells are in agricultural areas. The Mexican regulation does not make recommendations on the maximum permissible limit of this parameter; however, it is an important indicator of biodegradable organic contamination in water. The chemical oxygen demand (COD) values were similar to those of BOD5, so it can be inferred that there is no non-biodegradable biological contamination in this water, and the COD value corresponds to the biodegradable organic matter. Table7 shows the concentration of the physicochemical parameters observed in this study. Water 2020, 12, 556 9 of 26
Table 7. Physicochemical parameters in the water samples from the 10 sites: turbidity (NTU), color (Pt/Co), and sedimentable, dissolved, suspended and total solids,
total hardness, total alkalinity, chemical oxygen demand (COD) and biochemical oxygen demand (BOD5). Concentrations of solids, hardness, and alkalinity are expressed in mg/L. Concentrations of COD and BOD5 are expressed in mg O2/L.
Sampling Sedimentable Dissolved Suspended Total Total Total Site Turbidity Color COD BOD Campaign (2018) Solids Solids Solids Solids Hardness Alkalinity 5 May 1.4 5 0.1 378 4 382 193.8 181 5.4 3.5 P1 Nov 4.6 10 nd 378 6 384 164 194 3 1.85 May 1.66 5 0.1 496 4 500 238.08 243 4.7 3.2 P2 Nov 2.4 5 nd 486 4 490 240 235 5.4 3.55 May 1.35 5 nd 644 2 646 325.56 312 4.7 3.17 P3 Nov 2.4 5 0.1 608 4 612 320 300 4.8 3.2 May 1.41 5 nd 352 2 354 177.8 182 4.5 2.92 P4 Nov 2.5 5 nd 310 4 314 140 158 10.5 6.55 May 1.5 5 nd 382 2 384 190.2 194 3.9 2.45 P5 Nov 4.1 10 nd 378 2 380 200 187 3.4 2.24 May 2.4 5 nd 304 2 306 162.36 156 1.4 0.91 P6 Nov 2.5 5 nd 280 4 284 130 135 5.3 3.54 May 2.5 5 nd 300 2 302 151.44 163 17.6 11.36 P7 Nov 2.8 5 nd 304 4 308 136 151 5.8 3.89 May 3 10 0.1 322 6 328 165.08 169 19.2 12.5 P8 Nov 3.9 10 nd 302 4 306 142 158 8.5 5.16 May 4 10 0.2 262 16 278 143.28 146 15.7 10.2 P9 Nov 2.5 5 nd 252 2 254 120 124 5.5 3.5 May 2.3 5 0.1 256 2 258 132.36 138 10.1 6.25 P10 Nov 3.6 5 nd 270 2 272 130 131 11.8 7.67 NOM-127-SSA1-1994 - 5 20 - 1000 - - 500 - - - USEPA - 1 15 - 500 - - 500 - - - Water 2020, 12, 556 10 of 26
3.3. Major Ions
The COD values were similar to those of BOD5, so it can be inferred that there is no non-biodegradable biological contamination in this water, and the COD value corresponds to the biodegradable organic matter. Table4 shows the concentration of the physicochemical parameters observed in this study. Most of the substances dissolved in groundwater are in an ionic state. Some ions are almost always present, and their sum represents almost all the dissolved ions [18]. These major ions are Ca2+, 2+ + + 2 2 Mg , Na ,K , CO3 −, HCO3−, SO4 −, Cl−. It was observed that the predominant cations in this study were calcium and sodium, with magnesium and potassium in lower concentrations. These four species were found present in all samples during both sampling campaigns. Ca2+ is usually the main cation in most groundwater due to its widespread diffusion in igneous, sedimentary, and metamorphic rocks [19]. Mg2+, less abundant than Ca2+ in groundwater, comes from the dissolution of carbonate rock minerals, evaporites, dolomites, and the alteration of ferromagnesian silicates [20]. Na+ salts are highly soluble and tend to remain in solution because precipitation reactions do not occur among them, as is the case with Ca2+. However, Na+ can be adsorbed on clays with high cation exchange capacity and can be exchanged for Ca2+, causing a decrease in water hardness (natural softening) [21]. It is important to note that the highest concentrations of Na+ were shown at sites near the Duero River and the agricultural area, which could mean a contribution of this element to the water, but without exceeding the limits established by Mexican regulations. The natural origin of K+ in water is often a result of chemical weathering and the subsequent dissolution of minerals from nearby sedimentary rocks, as well as silicate and clay minerals [22]. In waters with pH close to 8.3, such as most groundwater, the dominant carbonated species is 2 HCO3−, while CO3 − begins to form at higher values [1]. The predominant anion in this study was 2 HCO3−, while no CO3 − was observed at three sites. 2 No site exceeded the normativity recommendation regarding SO4 − concentration, another important nutrient, considered to be a major anion in any type of water. All sites showed the presence 2 of SO4 − in both sampling campaigns, indicating the highest concentrations during the dry season at most points. This ion was the second predominant major anion. The presence of phosphorus was observed in both samplings. The most abundant chemical form 3 of this element in water is PO4 −, considered one of the primary nutrients in the water, and together 2 with HCO3−, Cl− and SO4 −, it is one of the major anions that contribute to the ionic equilibrium of water along with the cation group. Except for evaporites and rocks of marine origin, rocks usually have a low proportion of Cl−. Furthermore, this ion does not form low solubility salts, and it does not oxidize or reduce in groundwater, it is not significantly absorbed or becomes part of biochemical processes, properties that make it an ideal tracer [15]. N-NO3− may be present in groundwater as a result of the dissolution of rocks containing them or due to the anthropogenic activity of the area [23]. The importance of the determination of N-NO3− and N-NH3 is that they are some of the main indicators of ancient (NO3−) and recent (N-NH3) organic contamination, expressing the excellent oxidation in the water. Moreover, being very soluble and movable, both are the most common forms of nitrogen in groundwater [4]. N-NH3 appears as a trace species in natural groundwater, increasing its concentration when the medium is strongly reducing. This compound is the final product of the reduction of nitrogenous organic or inorganic substances that are naturally incorporated into groundwater. On the other hand, since the presence of ammonium promotes microbial proliferation, its detection in significant concentration in water is considered a mark of recent contamination. In this study, it was observed that N-NO3− concentration remained below the limit recommended by both Mexican drinking water regulations and the USEPA of 10 mg/L, while N-NH3 exceeded the Mexican recommendation of 0.5 mg/L in three sites. No point exceeded the Water 2020, 12, 556 11 of 26
USEPA’s recommendation for drinking water (6 mg/L). The sites with higher concentrations of N-NH3 are located near the growing area, which can also lead to a nitrogen contribution to water. It is important to note that the highest concentrations of all ions were observed during the spring sampling campaign, which may be due to the rock mineralization process and dilution in the rainy 2+ + 2+ season. The order of abundance of major ions in this study is HCO3− > Ca > Na > Mg > Cl− SO 2 > K+ > CO 2 > PO 3 N-NO > N-NH . Table8 shows the concentration of the major ≈ 4 − 3 − 4 − ≈ 3− 3 ion analyzed in this study, and Figures3 and4 show spatial distribution of these parameters in the study area.
3.4. Trace Elements The presence of some trace elements was observed. Mn, Ba, V, Fe, Sb, Co, and As were found at all sites. Copper and aluminum concentrations were also observed in five sites. No element exceeded the recommendations of both Mexican and international regulations. All concentrations were found at least in one order of magnitude below the regulation recommendations for drinking water. No Cr, Ni, Zn, Cd, or Pb were found. Table9 shows the concentration of the trace elements analyzed in this study. The presence of as in groundwater may have different sources including hydrothermal volcanism, oxidation of sulfurous minerals, desorption from the mineral in response to increased pH or concentration due to evaporation. The limit set by the Mexican standards of 25 g/L was exceeded in some sites. Fe is a trace element present in most groundwater. It is an essential element in human nutrition [4]. All sites are within the limit established by the Mexican regulations of 300 µg/L. Mn is one of the most abundant metallic elements in natural water. It is present in igneous and metamorphic rocks as a minor constituent. Mn2+ salts have high solubility, but under aeration conditions, they are oxidized precipitating oxyhydroxides. The chemistry of the Mn is similar to that of the Fe. The highest concentration of this element was observed during the dry season at all collection sites, but the limit allowed by Mexican regulations of 150 g/L was not exceeded. Ba is not considered an essential element in human nutrition. On some levels can cause heart damage, nerves, and blood vessels, and can even cause death [4]. This element was observed in all sites, in concentrations under the Mexican and USEPA regulations of 700 and 2000 g/L, respectively. Al constitutes approximately 8% of the Earth’s crust. It exists in nature, forming different stable minerals such as silicates and oxides. It is usually found in the form of pure aluminum silicate or combined with other metals such as Na, K, Fe, Ca, and Mg, but never as a free metal, such as potassium, sodium, or aluminum feldspars. This trace element was observed in three sampling sites. None of these sites exceeded the concentration indicated by the Mexican and USEPA regulations of 200 g/L. Although Sb can be found free, it is generally in its mineral form, mainly as sulfides. The biogeochemical behavior of antimony is similar to that of arsenic and phosphorus. In recent years there has been an increase of this metalloid in the environment due to anthropogenic activities, mainly due to emissions from vehicles, smelters, and the burning of municipal waste. This element was found on all sites in both sampling campaigns, in concentrations below the indication of USEPA regulation of 10 g/L. The chemical behavior of Co is similar to that of iron and nickel, both in the free and combined state. It is widely distributed in nature and is found in Fe, Ni, Cu, Ag, Mn, and Zn ores. Its main minerals are arsenides, oxides, and sulfides. It is also present in air, water, soil, plants, and animals. This metal can also be in the air and water and deposited on the soil through wind and dust. This element was observed in all sites. There is no water regulation on this element. Water 2020, 12, 556 12 of 26
Table 8. Major ions in the water samples from the 10 sites expressed in mg/L: calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), acid carbonate 2 2 3 (HCO3−), carbonate (CO3 −), sulfate (SO4 −), phosphate (PO4 −), chloride (Cl−), nitrate (N-NO3−), ammoniacal nitrogen (N-NH3), and the ionic balance (%).
Sampling Ionic Site Ca2+ Mg2+ Na+ K+ HCO CO 2 SO 2 PO 3 Cl N-NO N-NH Campaign (2018) 3− 3 − 4 − 4 − − 3− 3 Balance May 68.58 5.47 27.60 - 173.00 45.90 45.90 0.0587 32.14 0.076 0.3578 4 P1 Nov 36.00 18.00 41.86 12.10 184.00 12.00 41.73 0.027 31.41 0.1514 0.2452 2.2 May 72.70 13.62 44.85 - 283.00 62.86 62.86 0.0771 44.63 0.765 0.1193 3.9 P2 Nov 59.60 23.35 41.63 16.96 225.00 10.00 50.63 0.139 42.82 1.1985 0.0613 5.9 May 118.02 7.42 52.44 - 312.00 85.12 85.12 0.103 61.23 1.133 0.0596 3.6 P3 Nov 70.40 35.02 48.30 21.00 300.00 2+ 2+ + + 3 2 FigureFigure 3. 3.Distribution Distribution of of the the major major ions ions content content (mg (mg/L):/L): Ca Ca,2+ Mg, Mg2+,, Na Na+,K, K+, PO43−−, ,and and SO SO424− in− inthe the studiedstudied zone. zone. Water 2020, 12, 556 14 of 26 Water 2020, 12, x FOR PEER REVIEW 12 of 25 - 2 2- - - FigureFigure 4. 4.Distribution Distribution of of the the major major ions ions content content (mg (mg/L):/L): HCO HCO3−,3 CO, CO3 3−, ClCl−, ,N N-NO-NO33, −N, N-NH-NH3, 3and, and TDS TDS inin the the studied studied zone. zone. Water 2020, 12, 556 15 of 26 Table 9. Concentrations of trace elements in the water samples from the 10 sites (g/L): arsenic (As), iron (Fe), manganese (Mn), barium (Ba), aluminum (Al), antimony (Sb), cobalt (Co), vanadium (V), and copper (Cu). Sampling As Fe Mn Ba Al Sb Co V Cu Site Campaign (2018) (µg/L) (µg/L) (µg/L) (µg/L) (µg/L) (µg/L) (µg/L) (µg/L) (µg/L) May 0.392 2.930 0.937 13.807 V is a trace element that accumulates in humans due to the intake of wheat, soy, or olive oil, but despite being essential, when ingested in concentrations higher than those required can cause health effects. This metal was found in all sites. There are no Mexican or USEPA regulations for this element. Cu is an essential nutrient for humans. Drinking water usually contains less than 0.1 mg/L. However, some groundwater may have higher concentrations of this metal since it is an element naturally found in rocks and soil. Its presence was observed only in five sampling sites, with a concentration below the Mexican and USEPA regulations of 2000 and 1000 g/L, respectively. 3.5. Chemical Speciation of Trace Elements The study of the speciation or chemical mobility of the elements is essential for understanding and predicting the behavior and the impact they may have on any environmental system. The chemical mobility of a metal depends on its oxidation state, pH, and redox potential, as well as its interactions with other components of the system [24]. The chemical speciation was calculated with the Visual MINTEQ program (version 3.1). This paper reports the chemical speciation of As, Fe, Mn, Ba, and V, elements found in significant concentration. 3.5.1. Arsenic Arsenic is found in natural water as dissolved species As (III) or As (V), As (III) being the most 2 3 labile and biotoxic state. As (V) is usually found as H2AsO4−, HAsO4 − y AsO4 −, while As (III) is found + 2 as H4AsO3 ,H2AsO3−, HAsO3 −. Arsenic is easily mobilized in the pH values typical of groundwater, 2 from 6.5 to 8.5 [4]. The chemical form of As in the studied sites was predominantly HAsO4 − (about 85%) and in a smaller proportion H2AsO4−. According to Salcedo et al. [4], these chemical forms of As (V) usually predominate in the pH range observed in this study (6.7 to 8.4) and positive values of redox potential. An oxidizing system is inferred. 3.5.2. Iron Fe is usually found in groundwater in the form of Fe2+, although it can be presented as Fe3+, FeOH2+, or FeOH+, depending on pH, oxygen content, and chemical interaction with other elements [1]. At pH values of 4.5 to 9, soluble Fe is usually in a ferrous state, especially if the medium is reducing as in most groundwater. Fe oxidizes under the action of air or by contact with chlorine, going into the + ferric state and can thus be hydrolyzed to give an insoluble iron hydroxide [25]. In this study, Fe(OH)2 presence is observed as a predominant species (about 80%) in most of the studied sites. Fe(OH)4− and Fe(OH)3(aq) were also observed in smaller proportions as expected, according to the pH values of this study. Fe(OH)4− species showed a more significant presence in sites with pH around 8.5 and positive redox potential. 3.5.3. Manganese 2+ + Mn can be found in groundwater as free ion Mn or as MnHCO3 . It is often found in concentrations lower than Fe. Manganese salts are generally more soluble in acidic solutions than in 2+ alkaline solutions. In this study, Mn was found mainly as Mn (about 86%) and forming MnCO3(aq) (about 8%). MnCO3(aq) was found in higher concentrations at sites with pH values close to 8 and with + higher carbonate content. In a smaller proportion, MnCO3(aq), MnSO4(aq), and MnHCO3 complex were also observed in all sites. 3.5.4. Barium The main sources of Ba in the water are the erosion of natural deposits, runoff in crop areas, or industrial wastewater. Barium is also found in limestones, sandstones, and occasionally in soils. The concentration of this element in groundwater comes mainly from the dissolution of barite (BaSO4), increasing in reducing environments. It is usually found in groundwater in the form of Ba2+ [26]. Water 2020, 12, 556 17 of 26 2+ In this study, as expected, this metal was observed mainly as Ba (around 95%), followed by BaSO4(aq) (around 2.3%) and BaHCO3(aq) (around 2.3%). 3.5.5. Vanadium V is an abundant element in the earth’s crust that is forming minerals with other elements. Its chemical mobility increases under oxidizing and alkaline conditions [27,28]. It can occur with different oxidation states, with V(II) being the least stable in the environment. V(III) is more stable than V(II), but it also gradually oxidizes in the presence of air or dissolved oxygen, with V(V) being the predominant form in water exposed to atmospheric oxygen, while V(IV) can become predominant in reducing environments [29]. It was observed in the studied area that this element was found as 2+ + VOH (almost 100% in P4 to P7 and P9, P10), and as V(OH)2 (almost 100% in P1 to P3 and P8); being V(III) the expected chemical species according to the pH range found and to the absence of oxygen in groundwater. 3.6. Hydrogeochemistry 3.6.1. Hydrochemical Facies Piper diagram is a useful tool to identify different hydrochemical facies or origins of groundwater by plotting the content of cations and major anions in groundwater, indicating the origin, source of dissolved salts and processes that affect the characteristics of these natural waters [18,22] The hydrochemical diagram was constructed using AquaChem 2014.2 software. Figure5 shows the types of water in all 2+ studied sites. A bicarbonated-calcic water type (Ca -HCO3−) was observed in all samples, indicating that all sites belong to the same aquifer. This type of water is characterized by a low mineralization, low alkalinity, and short residence time in the aquifer. The groundwater with the shortest residence time in the aquifer is generally bicarbonated, then it is sulfated, and the water with the highest permanence is chlorinated. This evolution is called the Chevotareb sequence. In the cationic composition, the analogous sequence would be: Ca2+ with the 2+ + shortestWater 2020 residence, 12, x FOR PEER time, REVIEW then Mg , and finally Na with the highest residence time in the aquifer.16 of 25 Figure 5. Piper diagram of the studied sites. 3.6.2. Hydrochemical Diagrams Hydrogeochemical diagrams are a graphical representation of the chemical characteristics of groundwater [30]. AquaChem 2014.2 software was used in the construction of these diagrams. Figure 6 shows the location of the sampling sites in the Giggenbach triangular diagram. This scheme shows that all samples were in the immature water area, one of the main properties of cold groundwater. This type of water is characterized by not reaching equilibrium, i.e., they have a no chemical equilibrium with respect to the aquifer rock, where dissolution dominates when mixed with groundwater, and ionic exchange occurs [31]. According to Giggenbach [32], immature waters are inadequate for the evaluation of equilibrium temperatures. This result confirms that the chemical composition of groundwater is mainly controlled by the chemical dissolution of the rock [18]. Figure 6. Giggenbach diagram of the studied sites. Water 2020, 12, x FOR PEER REVIEW 16 of 25 Water 2020, 12, 556 18 of 26 Figure 5. Piper diagram of the studied sites. 3.6.2.3.6.2. HydrochemicalHydrochemicalDiagrams Diagrams HydrogeochemicalHydrogeochemical diagramsdiagrams are are aa graphicalgraphical representationrepresentation ofof thethe chemicalchemical characteristicscharacteristics ofof groundwatergroundwater [ 30[30].]. AquaChemAquaChem 2014.22014.2 softwaresoftware waswas usedused in in the the construction construction of of these these diagrams. diagrams. FigureFigure6 shows6 shows the the location location of the of samplingthe sampling sites insites the Giggenbachin the Giggen triangularbach triangular diagram. diagram. This scheme This showsscheme that shows all samples that all were samples in the were immature in the water immature area, onewater of thearea, main one properties of the main of coldproperties groundwater. of cold Thisgroundwater. type of water This is characterizedtype of water by is not characterized reaching equilibrium, by not reaching i.e., they equilibrium have a no chemical, i.e., they equilibrium have a no withchemical respect equilibrium to the aquifer with rock, res wherepect to dissolution the aquifer dominates rock, where when dissolution mixed with dominates groundwater, when and mixed ionic exchangewith groundwater, occurs [31]. and According ionic exchange to Giggenbach occurs [ 32[31].], immature According waters to Giggenbach are inadequate [32], forimmature the evaluation waters ofare equilibrium inadequate temperatures. for the evaluation This of result equilibrium confirms temperatures. that the chemical This result composition confirms of that groundwater the chemical is mainlycomposition controlled of groundwater by the chemical is mainly dissolution controlled of the by rock the [chemical18]. dissolution of the rock [18]. FigureFigure 6. 6.Giggenbach Giggenbach diagramdiagram ofof thethe studiedstudied sites. sites. The Schöeller diagram shows the absolute value of each major ion and identifies the highest concentrations [23]. Figure7 presents this diagram, which shows Ca 2+ as the dominant cation, while the dominant anion is HCO3−, confirming the information obtained in the diagrams above. The evaporation rate, the chemical composition of the rock, and the rainwater generally control the chemistry of the groundwater [33]. The Gibbs diagram shows the mechanisms that control the chemistry of groundwater from the relationship of chemical components with their respective lithologies in the aquifer [34], representing the domain of precipitation, of evaporation and the water–rock interaction [35]. This diagram is useful for assessing the geological origin of chemical constituents in groundwater samples [36], where the concentration of TDS is plotted against a ratio of cation and anion concentration. Figures8 and9 show that the domain of water–rock interaction controls the chemistry of groundwater in the studied area, where the main process that affects the chemistry of water is the dissolution of carbonates and silicates. This process of water–rock interaction includes the chemical weathering of rocks, the dissolution-precipitation of secondary carbonates, and the ionic exchange between water and clay minerals in the area. Water 2020, 12, x FOR PEER REVIEW 17 of 25 The Schöeller diagram shows the absolute value of each major ion and identifies the highest Waterconcentrat2020, 12,ions 556 [23]. Figure 7 presents this diagram, which shows Ca2+ as the dominant cation, while19 of 26 the dominant anion is HCO3−, confirming the information obtained in the diagrams above. Water 2020, 12, x FOR PEER REVIEW 18 of 25 Diagrama de Gibbs Water 2020, 12, x FOR PEER REVIEW 18 of 25 10000 Evaporation FigureFigure 7.7.Diagrama Schöeller diagram de ofGibbs the studied sites. sites. 1000 10000 Water-rock The evaporation rate, the chemical composition of the rock, and the rainwater generally control interaction Evaporation the chemistry of the100 groundwater [33]. The Gibbs diagram shows the mechanisms that control the chemistry of groundwater1000 from the relationship of chemicalPrecipitation components with their respective lithologies in SDT (mg/L) the aquiferWater [34],-rock representing the domain of precipitation, of evaporation and the water–rock interaction10 [35].interaction 100 This diagram is useful for assessing the geological origin of chemical constituents in Precipitation groundwater samples [36], where the concentration of TDS is plotted against a ratio of cation and SDT SDT (mg/L) 1 anion concentration.100.25 Figures 8 and 90.3 show that the 0.35domain of water0.4–rock interaction0.45 controls the chemistry of groundwater in the studied area,(Na++K where+)/(Na the++K main++Ca process2+) that affects the chemistry of water is the dissolution of carbonates and silicates. This process of water–rock interaction includes 1 the chemical weathering of rocks, the dissolution-precipitation of secondary carbonates, and the Figure0.25 8. Gibbs diagram0.3 of the studied0.35 sites related to major0.4 cations. 0.45 ionic exchange between water and clay minerals in the area. (Na++K+)/(Na++K++Ca2+) Figure 8. Gibbs diagramDiagrama of the studied de Gibbs sites related to major cations. Figure 8. Gibbs diagram of the studied sites related to major cations. 10000 Evaporation Diagrama de Gibbs 1000 10000 Water-rock interaction Evaporation 100 1000 Precipitation SDT SDT (mg/L) Water-rock 10 interaction 100 Precipitation SDT SDT (mg/L) 1 100.15 0.17 0.19 0.21 0.23 0.25 0.27 0.29 - - - Cl /(Cl +HCO3 ) Figure1 9. Gibbs diagram of the studied sites related to major anions. Figure0.15 9. Gibbs0.17 diagram0.19 of the studied0.21 sites0.23 related to0.25 major anions.0.27 0.29 - - - Cl /(Cl +HCO3 ) 3.6.3. Binary Ratios and Geochemical Processes HydrogeochemicalFigure molar 9. Gibbs ratios diagram are aof useful the studied tool sitesto determine related to majorthe origin anions. of groundwater, and they allow understanding the reactions that occur on its way from the recharge zones to the 3.6.3.discharge Binary points. Ratios They and haveGeochemical a direct relationshipProcesses with the materials through which water circulates and withHydrogeochemical the phenomena molar that change ratios areits compositiona useful tool [36].to determine In this work, the origindifferent of ionicgroundwater, relationships and theywere allowevaluated understanding to understand the the reactions groundwater that occurchemistry on itsin the way urban from area the of recharge Zamora, zones Michoacán. to the dischargeThe weathering points. They that have affects a direct some relationship silicates that with provide the mat sodiumerials throughto the w aterwhich can water alter circulatesthe value + − + andof the with Na the/Cl phenomenaratio ratio. Ifthat the change halite solutionits composition is responsible [36]. In for this the work, presence different of Na ionic, this relationships molar ratio + wereis approximately evaluated to 1 understand [37]. On the the other groundwater hand, if the chemistry value of thisin the ratio urban is >1, area it canof Zamora, be assumed Michoacán. that Na is releasedThe weathering from a weathering that affects reaction some withsilicates silicates that provide[18], with sodium an ion -toexchange the water process can alter [22,38]. the Invalue the + − ofcurrent the Na studied+/Cl− ratio area, ratio. the If Na the/Cl halite molar solution ratio isvaried responsible from 1.268 for the to presence1.861, with of Naan +average, this molar of 1.616, ratio + iswhich approximately means that 1 all[37]. samples On the show other Na hand, release if the as value a result of this of aratio silicate is >1, weathering it can be assumed reaction thatprocess, Na+ isas released demonstrated from a by weathering hydrochemical reaction facies. with silicates [18], with an ion-exchange process [22,38]. In the 2+ 2+ currentWhen studied the values area, theof the Na Ca+/Cl−/Mg molarratio ratio are varied close tofrom 1.0, 1.268they indicateto 1.861, groundwater with an average controlled of 1.616, by whichthe dolomite means solution,that all samples while values show Nabetween+ release 1 and as a 2 result show of the a silicatedissolution weathering of the calcite. reaction In process, natural as demonstrated by hydrochemical facies. When the values of the Ca2+/Mg2+ ratio are close to 1.0, they indicate groundwater controlled by the dolomite solution, while values between 1 and 2 show the dissolution of the calcite. In natural Water 2020, 12, 556 20 of 26 3.6.3. Binary Ratios and Geochemical Processes Hydrogeochemical molar ratios are a useful tool to determine the origin of groundwater, and they allow understanding the reactions that occur on its way from the recharge zones to the discharge points. They have a direct relationship with the materials through which water circulates and with the phenomena that change its composition [36]. In this work, different ionic relationships were evaluated to understand the groundwater chemistry in the urban area of Zamora, Michoacán. The weathering that affects some silicates that provide sodium to the water can alter the value of + + the Na /Cl− ratio ratio. If the halite solution is responsible for the presence of Na , this molar ratio is approximately 1 [37]. On the other hand, if the value of this ratio is >1, it can be assumed that Na+ is released from a weathering reaction with silicates [18], with an ion-exchange process [22,38]. In the + current studied area, the Na /Cl− molar ratio varied from 1.268 to 1.861, with an average of 1.616, which means that all samples show Na+ release as a result of a silicate weathering reaction process, as demonstrated by hydrochemical facies. When the values of the Ca2+/Mg2+ ratio are close to 1.0, they indicate groundwater controlled by the dolomite solution, while values between 1 and 2 show the dissolution of the calcite. In natural waters where this proportion is greater than 2, the dissolution of silicate minerals that contribute to the enrichment of Ca2+ and Mg2+ in groundwater can be assumed [22,35]. In the studied area, relationships between 2.18 and 5.43 were observed, with an average of 3.13, indicating a process of dissolution of the silicate minerals, providing Ca2+ and Mg2+ from the rock to the groundwater. When the values of the Na+/K+ ratio are close to 1.0, they indicate groundwater controlled by the dolomite solution, while values between 1 and 2 show the dissolution of the calcite. In natural waters where this proportion is greater than 2, the dissolution of silicate minerals that contribute to the enrichment of Ca2+ and Mg2+ in groundwater can be assumed [22,35]. In the studied area, relationships between 2.18 and 5.43 were observed, with an average of 3.13, indicating a process of dissolution of the silicate minerals, providing Ca2+ and Mg2+ from the rock to the groundwater. 2+ 2 Low values of the Ca /SO4 − ratio indicate the elimination of calcium, either by precipitation as calcium carbonate, by ion-exchange processes, or both. These two processes are more abundant 2+ 2 in shallow groundwater than in deep groundwater. Water with high Ca /SO4 − ratios indicates the addition of calcium from the weathering of minerals rich in this element, other than gypsum [39]. In the studied area, values of this relationship between 2.25 and 3.56 were obtained, with an average of 3.03, showing weathering of Ca2+ processes from the aquifer rock. 2+ The effect of the water–rock interaction predominates if the Mg /Cl− ratio is higher than 1.0, which indicates a more significant contribution of magnesium to the water as a result of the dissolution of magnesium silicates [40]. In the studied area, this proportion was observed between 0.91 and 1.64, with an average of 1.26. The interaction between water and rock prevail in most sites with a contribution of Mg2+ as a result of the dissolution of magnesium silicates. The ratio was less than 1.0 only at P8 site, showing a greater depth of the water. Values greater than 1.0 of HCO3−/Cl− ratio are frequently observed in cold groundwater, with a short flow path and rapid circulation. Values under 1.0 indicate the presence of thermal water, with greater subsurface flow path and deep circulation [41]. In this study area, a range from 2.90 to 4.26 was obtained, indicating the presence of cold water of short and rapid path through the aquifer. Figure 10 shows that 100% of the analyzed samples are under the 1:1 slope. This fact indicates that 2+ 2+ there is a deficiency of Ca and Mg compared to HCO3−. Thus, it is confirmed that HCO3− also comes from processes other than the dissolution of calcite or dolomite. In this case, and as established by the ionic relationships, it is supplied by the weathering of the silicates. Water 2020, 12, x FOR PEER REVIEW 19 of 25 waters where this proportion is greater than 2, the dissolution of silicate minerals that contribute to the enrichment of Ca2+ and Mg2+ in groundwater can be assumed [22,35]. In the studied area, relationships between 2.18 and 5.43 were observed, with an average of 3.13, indicating a process of dissolution of the silicate minerals, providing Ca2+ and Mg2+ from the rock to the groundwater. When the values of the Na+/K+ ratio are close to 1.0, they indicate groundwater controlled by the dolomite solution, while values between 1 and 2 show the dissolution of the calcite. In natural waters where this proportion is greater than 2, the dissolution of silicate minerals that contribute to the enrichment of Ca2+ and Mg2+ in groundwater can be assumed [22,35]. In the studied area, relationships between 2.18 and 5.43 were observed, with an average of 3.13, indicating a process of dissolution of the silicate minerals, providing Ca2+ and Mg2+ from the rock to the groundwater. Low values of the Ca2+/SO42- ratio indicate the elimination of calcium, either by precipitation as calcium carbonate, by ion-exchange processes, or both. These two processes are more abundant in shallow groundwater than in deep groundwater. Water with high Ca2+/ SO42− ratios indicates the addition of calcium from the weathering of minerals rich in this element, other than gypsum [39]. In the studied area, values of this relationship between 2.25 and 3.56 were obtained, with an average of 3.03, showing weathering of Ca2+ processes from the aquifer rock. The effect of the water–rock interaction predominates if the Mg2+/Cl− ratio is higher than 1.0, which indicates a more significant contribution of magnesium to the water as a result of the dissolution of magnesium silicates [40]. In the studied area, this proportion was observed between 0.91 and 1.64, with an average of 1.26. The interaction between water and rock prevail in most sites with a contribution of Mg2+ as a result of the dissolution of magnesium silicates. The ratio was less than 1.0 only at P8 site, showing a greater depth of the water. Values greater than 1.0 of HCO3-/Cl- ratio are frequently observed in cold groundwater, with a short flow path and rapid circulation. Values under 1.0 indicate the presence of thermal water, with greater subsurface flow path and deep circulation [41]. In this study area, a range from 2.90 to 4.26 was obtained, indicating the presence of cold water of short and rapid path through the aquifer. Figure 10 shows that 100% of the analyzed samples are under the 1:1 slope. This fact indicates that there is a deficiency of Ca2+ and Mg2+ compared to HCO3-. Thus, it is confirmed that HCO3- also Watercomes2020 from, 12, 556 processes other than the dissolution of calcite or dolomite. In this case, and21 of as 26 established by the ionic relationships, it is supplied by the weathering of the silicates. 2+ 2+ - Ca + Mg vs HCO3 7 6 5 (meq/L) 4 2+ 2+ 3 +Mg 2+ 2 Ca 1 0 0 1 2 3 4 5 6 7 - HCO3 (meq/L) SitiosGroundwater de estudio wells Water Figure2020, 12 10.,10. x FOR BinaryBinary PEER hydrogeochemicalhydrogeochemical REVIEW diagram diagram of of the the dissolution dissolution of calciteof calcite or dolomite or dolomite in the in study the study area.20 of 25 area. 2 Figure 11 presentspresents thethe relationshiprelationship betweenbetween SOSO442−− and Cl−.. All All samples samples in in this this area obtainedobtained 2 SO42−− asas a aresult result of of the the rainwater rainwater supply, supply, and and there there is is no no interaction interaction due due to rock composition. There is no anthropogenic contamination since the concentrations are relativelyrelatively low.low. Figure 11. BinaryBinary diagram diagram showing showing the origin of sulf sulfatesates in groundwater in the studied area. 3.6.4. Ion Ion Exchange The chemical reactions in which ion exchange occurs between groundwater and the aquifer environment duringduring residence residence and an movementd movement periods periods can becan understood be understood through through the study the of study alkaline of alkalinechlorine indiceschlorine [34 indices]. Schöeller [34]. [42 Schöeller] established [42] an esta indexblished to identify an index the ion-exchange to identify processesthe ion-exchange between processesgroundwater between and its groundwater surroundings and during its surroundings residence as it during passes throughresidence the as aquifer. it passes Chloro through Alkaline the aquifer.Indices (CAI)Chloro can Alkaline be positive Indices or negative (CAI) can depending be positive on the or exchangenegative ofdepending sodium and on potassiumthe exchange in the of sodiumrock with and magnesium potassium and in the calcium rock inwith the magnesium water and viceand versacalcium [43 ].in Thethe water positive and CAI vice indicates versa [43]. the The positive CAI indicates the exchange of Na+ and K+ of the water with Mg2+ and Ca2+ of the rocks, and the negative indicates that there is an exchange of Mg2+ and Ca2+ of the water with Na+ and K+ of the rocks [18,36]. In the study area, a negative alkaline chlorine index was obtained, indicating the ionic exchange of Mg2+ and Ca2+ from the water with Na+ and K+ ions from the rock this because it is not a saline intrusion zone (Table 10). Equations (5) and (6) express the CAI. The concentrations are in meq/L: Cl- − Na++K+ CAI 1= (5) Cl- Cl- − Na++K+ CAI 2= 2- - 2- - (6) SO4 +HCO3+CO3 +NO3 Table 10. Molar ratio values of the groundwater of Zamora, Michoacán. SITE Na+/Cl− Ca2+/Mg2+ Na+/K+ Ca2+/SO42− Mg2+/Cl− HCO3−/Cl− CAI 1 CAI 2 P1 1.689 4.409 4.878 2.824 1.084 3.265 −1.034 −0.195 P2 1.524 2.393 4.333 2.797 1.240 3.368 −0.876 −0.165 P3 1.268 5.433 4.077 2.723 1.010 2.903 −0.579 −0.118 P4 1.861 2.349 3.018 2.249 1.477 3.637 −1.472 −0.263 P5 1.379 2.630 3.450 2.517 1.492 3.245 −0.779 −0.148 P6 1.616 2.563 2.516 3.371 1.262 3.363 −1.260 −0.242 P7 1.762 2.643 3.789 3.349 1.119 3.461 −1.227 −0.231 Water 2020, 12, 556 22 of 26 exchange of Na+ and K+ of the water with Mg2+ and Ca2+ of the rocks, and the negative indicates that there is an exchange of Mg2+ and Ca2+ of the water with Na+ and K+ of the rocks [18,36]. In the study area, a negative alkaline chlorine index was obtained, indicating the ionic exchange of Mg2+ and Ca2+ from the water with Na+ and K+ ions from the rock this because it is not a saline intrusion zone (Table 10). Equations (5) and (6) express the CAI. The concentrations are in meq/L: + + Cl− Na +K CAI 1 = − (5) Cl− + + Cl− Na +K CAI 2 = − (6) 2 2 SO4−+HCO3−+CO3−+NO3− Table 10. Molar ratio values of the groundwater of Zamora, Michoacán. + 2+ 2+ + + 2+ 2 2+ SITE Na /Cl− Ca /Mg Na /K Ca /SO4 − Mg /Cl− HCO3−/Cl− CAI 1 CAI 2 P1 1.689 4.409 4.878 2.824 1.084 3.265 1.034 0.195 − − P2 1.524 2.393 4.333 2.797 1.240 3.368 0.876 0.165 − − P3 1.268 5.433 4.077 2.723 1.010 2.903 0.579 0.118 − − P4 1.861 2.349 3.018 2.249 1.477 3.637 1.472 0.263 − − P5 1.379 2.630 3.450 2.517 1.492 3.245 0.779 0.148 − − WaterP6 2020, 12,1.616 x FOR PEER REVIEW 2.563 2.516 3.371 1.262 3.363 1.260 0.24221 of 25 − − P7 1.762 2.643 3.789 3.349 1.119 3.461 1.227 0.231 − − P8 1.602 3.568 3.563 3.386 0.912 3.647 1.054 0.190 P8 1.602 3.568 3.563 3.386 0.912 3.647 −1.054− −0.190− P9 1.828 3.101 2.727 3.540 1.330 4.260 1.490 0.232 P9 1.828 3.101 2.727 3.540 1.330 4.260 −1.490− −0.232− P10 1.631 2.179 3.003 3.555 1.641 3.830 1.182 0.205 P10 1.631 2.179 3.003 3.555 1.641 3.830 −1.182− −0.205− FiguresFigures 1212 andand 1313 showshow CAICAI 11 andand CAICAI 22 typestypes obtained,obtained, respectively.respectively. 1.400 0.900 - 0.400 )]/Cl + +K + -0.100 0 1 2 3 4 5 6 7 8 9 10 (Na - - -0.600 [Cl -1.100 -1.600 Sampling sites FigureFigure 12.12. Chloro Alkaline Index type 1 (CAI 1) to determine the type of ion exchange occurred inin thethe studiedstudied area.area. 0.200 ) - 0.150 2 4 0.100 +SO - 3 0.050 +HCO 0.000 - 0 1 2 3 4 5 6 7 8 9 10 -0.050 )]/(Cl + -0.100 +K + (Na -0.150 - - [Cl -0.200 -0.250 Sampling Sites Figure 13. Chloro Alkaline Index type 2 (CAI 2) to determine the type of ion exchange occurred in the studied area. 3.7. Water Quality Index The weighted arithmetic average method was used in these calculations. This method for calculating the WQI considers the maximum permissible limits for any regulations, whether national [13] or international [44], and can be adapted to the needs of the type of study being carried out. However, it has certain limitations, such as that it is not possible to evaluate all the risks present in the water, and the weighting required for each parameter according to its importance could become subjective. Water 2020, 12, x FOR PEER REVIEW 21 of 25 P8 1.602 3.568 3.563 3.386 0.912 3.647 −1.054 −0.190 P9 1.828 3.101 2.727 3.540 1.330 4.260 −1.490 −0.232 P10 1.631 2.179 3.003 3.555 1.641 3.830 −1.182 −0.205 Figures 12 and 13 show CAI 1 and CAI 2 types obtained, respectively. 1.400 0.900 - 0.400 )]/Cl + +K + -0.100 0 1 2 3 4 5 6 7 8 9 10 (Na - - -0.600 [Cl -1.100 -1.600 Sampling sites Water Figure2020, 12 ,12. 556 Chloro Alkaline Index type 1 (CAI 1) to determine the type of ion exchange occurred in the23 of 26 studied area. 0.200 ) - 0.150 2 4 0.100 +SO - 3 0.050 +HCO 0.000 - 0 1 2 3 4 5 6 7 8 9 10 -0.050 )]/(Cl + -0.100 +K + (Na -0.150 - - [Cl -0.200 -0.250 Sampling Sites FigureFigure 13.13. ChloroChloro Alkaline Index type 2 (CAI 2) to determine the type of ion exchange occurred in the studied area. 3.7. Water Quality Index The weighted aarithmeticrithmetic average method was used in these calculations. This method for calculating thethe WQIWQI considers considers the the maximum maximum permissible permissible limits limits for for any any regulations, regulations, whether whether national national [13] or[13] international or international [44], and[44], can and be can adapted be adapted to the needsto the of needs the type of the of studytype of being study carried being out. carried However, out. itHowever, has certain it has limitations, certain limitations, such as that such it is as not that possible it is not to possible evaluate to all evaluate the risks all present the risks in present the water, in andthe water, the weighting and the weighting required for required each parameter for each accordingparameter toaccording its importance to its importance could become could subjective. become subjective.The results obtained in the studied area ranged between 30.4 and 72.4 (Table 11), observing water of excellent and good quality. Table 11. Water Quality Index in the urban zone of Zamora, Mexico. Site WQI Water Quality P1 38.29 Excellent P2 45.97 Excellent P3 59.02 Good P4 38.85 Excellent P5 41.01 Excellent P6 33.56 Excellent P7 71.35 Good P8 72.44 Good P9 36.16 Excellent P10 30.48 Excellent 4. Conclusions This study allows knowledge of the hydrogeochemistry and drinking water quality in the urban area of Zamora, Mexico, and may be useful for subsequent research since there is no previous information on the chemistry of water in this zone. The groundwater of the studied area presented a 2+ + slight tendency to alkalinity. The order of abundance of major ions in this study is HCO3− > Ca > Na > Mg2+ > Cl SO 2 > K+ > CO 2 > PO 3 N-NO > N-NH . The presence of Mn, Ba, V, Fe, Sb, − ≈ 4 − 3 − 4 − ≈ 3− 3 Co, and As was found at all sites. Copper and aluminum concentrations were also observed in five sites. No trace element exceeded the recommendations of both Mexican and international regulations for 2 + 2+ drinking water. The chemical mobility speciation of trace elements showed HAsO4 −, Fe(OH)2 , Mn , Water 2020, 12, 556 24 of 26 2+ 2+ + Ba , VOH , and V(OH)2 as the predominant species in the studied area. The hydrogeochemical 2+ facies are Ca -HCO3− in all sites, which means that probably all wells are supplied by the same aquifer, and the groundwater is of recent infiltration. Hydrochemical diagrams indicate young or immature, cold, non-saline, and uncontaminated water with short residence time. The water–rock interaction controls the chemistry of groundwater in the studied area, where the main process that affects the chemistry of water is the dissolution of carbonates and silicates. This process of water–rock interaction includes the chemical weathering of rocks, the dissolution-precipitation of secondary carbonates, and the ionic exchange between water and clay minerals in the area, as confirmed by the binary ratios. The water in the study area is suitable for human use and consumption according to Mexican and international regulations with excellent quality in 7 wells and good in the other 3. Author Contributions: Conceptualization, R.A.-C.-V. and R.C.-M.; methodology, C.A.R.-T.; software, C.A.R.-T.; validation, O.M.-B., E.H.-Á. and C.A.R.-T; formal analysis, R.A.-C.-V, O.B.-D and C.A.R.-T.; writing—original draft preparation, C.A.R.-T., R.A.-C.-V, and J.A.Á.-O.; writing—review and editing R.C.-M., J.A.Á.-O. and O.B.-D.; project administration, R.A.-C.-V. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by CIC-UMSNH, grant number CIC-2019 and The APC was funded by PRODEP. Acknowledgments: The authors wish to thank Juan Rangel Camarena for his valuable participation in the physicochemical analyses. Conflicts of Interest: The authors declare no conflict of interest. References 1. Ruiz, Á.; Cuenca, Á.; Agila, R.; Criollo, D.; Leiva, J.; Salazar, J. Hydrochemical characterization of groundwater in the Loja Basin (Ecuador). Appl. Geochem. 2019, 104, 1–9. [CrossRef] 2. Busico, G.; Cuoco, E.; Kazakis, N.; Colombani, N.; Mastrocicco, M.; Tedesco, D.; Voudouris, K. Multivariate statistical analysis to characterize/discriminate between anthropogenic and geogenic trace elements occurrence in the Campania Plain, Southern Italy. Environ. Pollut. 2018, 234, 260–269. [CrossRef] [PubMed] 3. Saravanan, K.; Srinivasamoorthy, K.; Prakash, R.; Gopinath, S.; Suma, C. An Evaluation of hydrogeochemistry of groundwater in upper vellar sub-basin using mineral stability and solute transport modelling. Aquat. Procedia 2015, 4, 1119–1125. [CrossRef] 4. Salcedo, E.; Garrido, S.; Vicenta, M.; Martínez, M.; Ocampo, A. Hydrogeochemistry and water-rock interactions in the urban area of Puebla Valley aquifer (Mexico). J. Geochem. Explor. 2017, 181, 219–235. [CrossRef] 5. Gnanachandrasamy, G.; Ramkumar, T.; Venkatramanan, S.; Vasudevan, S.; Chung, S.; Bagyaraj, M. Accessing groundwater quality in lower part of Nagapattinam district, Southern India: Using hydrogeochemistry and GIS interpolation techniques. Appl. Water Sci. 2015, 5, 39–55. [CrossRef] 6. CONAGUA. Actualización de la Disponibilidad Media Anual de Agua en el Acuífero Zamora, Estado de Michoacán. Zamora, Michoacán; DOF: Mexico City, México, 2015; pp. 1–26. 7. INEGI. Compendio de Información Geográfica Municipal 2010 Zamora, Michoacán de Ocampo; INEGI: Mexico city, Mexico, 2010. 8. INAFED. Instituto Para el Federalismo y el Desarrollo Municipal. Available online: http://www.inafed.gob. mx/work/enciclopedia/EMM16michoacan/municipios/16108a.html (accessed on 15 December 2019). 9. Alfaro, R.; Martínez, V.; Segovia, N.; Peña, P.; López, M.B.E.; Armienta, M.A.; Rangel, J.; Seidel, J.L. Radon behavior in springs and wells around Cuitzeo Lake, Lerma River basin. Geofís. Int. 2002, 41, 439–445. 10. APHA-WWA-WPC. Standard Methods for the Examination Water and Wastewater, 21st ed.; APHA-AWWA-WPCF, Ed.; APHA-AWWA-WPC: Washington, DC, USA, 2005. 11. Brown, R.M.; McClelland, N.I.; Deininger, R.A.; Tozer, R.G. A water quality index: Do we dare? Water Sew. Works 1970, 117, 339–343. 12. Sadat-Noori, S.; Ebrahimi, K.; Liaghat, A. Groundwater quality assessment using the Water Quality Index and GIS in Saveh-Nobaran aquifer, Iran. Environ. Earth Sci. 2014, 71, 3827–3843. [CrossRef] Water 2020, 12, 556 25 of 26 13. DOF. Modificación de la Norma Oficial Mexicana NOM-127-SSA1-1994. Salud Ambiental. Agua para uso y consumo humano. Límites permisibles de calidad y tratamientos a que debe someterse el agua para su potabilización. Secretaría de Salud. Diario Oficial de la Federación. 1994. Available online: http://www.salud.gob.mx/unidades/cdi/nom/m127ssa14.html (accessed on 9 February 2020). 14. Gubran, M.; Ghrefat, H.; Zaidi, F.; Shehata, M. Integration of hydrochemical, GIS, and remote-sensing data for assessment of shallow groundwater aquifers in Wadi Nisah, Central Saudi Arabia. Environ. Earth Sci. 2019, 78, 161. [CrossRef] 15. Nas, B.; Berktay, A. Groundwater quality mapping in urban groundwater using GIS. Environ. Monit. Assess. 2010, 160, 215–227. [CrossRef][PubMed] 16. Alacali, M. Hydrogeochemical investigation of geothermal springs in Erzurum, East Anatolia (Turkey). Environ. Earth Sci. 2018, 77, 802. [CrossRef] 17. Das, S.; Nag, S. Application of multivariate statistical analysis concepts for assessment of hydrogeochemistry of groundwater—A study in Suri I and II blocks of Birbhum District, West Bengal, India. Appl. Water Sci. 2017, 7, 873–888. [CrossRef] 18. Berhe, B.A.; Dokuz, U.E.; Çelik, M. Assessment of hydrogeochemistry and environmental isotopes of surface and groundwaters in the Kütahya Plain, Turkey. J. Afr. Earth Sci. 2017, 134, 230–240. [CrossRef] 19. Voutsis, N.; Kelepertzis, E.; Tziritis, E.; Kelepertsis, A. Assessing the hydrogeochemistry of groundwaters in ophiolite areas of Euboea Island, Greece, using multivariate statistical methods. J. Geochem. Explor. 2015, 159, 79–92. [CrossRef] 20. Wu, C.; Wu, X.; Qian, C.; Zhu, G. Hydrogeochemistry and groundwater quality assessment of high fluoride levels in the Yanchi endorheic region, northwest China. Appl. Geochem. 2018, 98, 404–417. [CrossRef] 21. Morán-Ramírez, J.; Ledesma-Ruíz, R.; Mahlknecht, J.; Ramos-Leal, J. Rock-water interactions and pollution processes in the volcanic aquifer system of Guadalajara, Mexico, using inverse geochemical modeling. Appl. Geochem. 2016, 68, 79–94. [CrossRef] 22. Redwan, M.; Moneim, A.A.A. Factors controlling groundwater hydrogeochemistry in the area west of Tahta, Sohag, Upper Egypt. J. Afr. Earth Sci. 2016, 118, 328–338. [CrossRef] 23. Khan, R.; Jhariya, D. Hydrogeochemistry and Groundwater Quality Assessment for Drinking and Irrigation Purpose of Raipur City, Chhattisgarh. J. Geol. Soc. India 2018, 91, 475–482. [CrossRef] 24. Gonzalez Flores, E.; Tornero Campante, M.A.; Angeles Cruz, Y.; Bonilla y Fernandez, N. Concentración total y especiación de metales pesados en biosólidos de origen urbano. Rev. Int. Cont. Amb. 2009, 25, 15–22. 25. Okan, Ö.Ö.; Kalender, L.; Çetinda˘g,B. Trace-element hydrogeochemistry of thermal waters of Karakoçan (Elazı˘g)and Mazgirt (Tunceli), Eastern Anatolia, Turkey. J. Geochem. Explor. 2018, 194, 29–43. [CrossRef] 26. Giménez-Forcada, E.; Vega-Alegre, M. Arsenic, barium, strontium and uranium geochemistry and their utility as tracers to characterize groundwaters from the Espadán–Calderona Triassic Domain, Spain. Sci. Total Environ. 2015, 512, 599–612. [CrossRef][PubMed] 27. Fiorentino, C.E.; Paoloni, J.D.; Sequeira, M.E.; Arosteguy, P. The presence of vanadium in groundwater of southeastern extreme the pampean region Argentina: Relationship with other chemical elements. J. Contam. Hydrol. 2007, 93, 122–129. [CrossRef][PubMed] 28. Paradis, C.J.; Johnson, R.H.; Tigar, A.D.; Sauer, K.B.; Marina, O.C.; Reimus, P.W. Field experiments of surface water to groundwater recharge to characterize the mobility of uranium and vanadium at a former mill tailing site. J. Contam. Hydrol. 2019, 229, 103581. [CrossRef][PubMed] 29. Pourret, O.; Dia, A.; Gruau, G.; Davranche, M.; Coz, M. Assessment of vanadium distribution in shallow groundwaters. Chemical Geol. 2012, 294–295, 89–102. [CrossRef] 30. Venkatramanan, S.; Chung, S.Y.; Ramkumar, T.; Gnanachandrasamy, G.; Vasudevan, S.; Lee, S. Application of GIS and hydrogeochemistry of groundwater pollution status of Nagapattinam district of Tamil Nadu, India. Environ. Earth Sci. 2015, 73, 4429–4442. [CrossRef] 31. Sharifi, R.; Moore, F.; Mohammadi, Z.; Keshavarzi, B. Estimation of deepwater temperature and hydrogeochemistry of springs in the Takab geothermal field, West Azerbaijan, Iran. Environ. Monit. Assess. 2016, 188, 75. [CrossRef] [PubMed] 32. Giggenbach, W.F. Geothermal solute equilibria. Derivation of Na-K-Mg-Ca geoindicators. Geochim. Cosmochim. Acta 1988, 52, 2749–2765. [CrossRef] Water 2020, 12, 556 26 of 26 33. Gaikwad, S.; Gaikwad, S.; Meshram, D.; Wagh, V.; Kandekar, A.; Kadam, A. Geochemical mobility of ions in groundwater from the tropical western coast of Maharashtra, India: Implication to groundwater quality. Environ. Dev. Sustain. 2019, 21, 1–34. [CrossRef] 34. Raju, N.J.; Shukla, U.K.; Ram, P. Hydrogeochemistry for the assessment of groundwater quality in Varanasi: A fast-urbanizing center in Uttar Pradesh, India. Environ. Monit. Assess. 2011, 173, 279–300. [CrossRef] 35. Sheikh, M.A.; Azad, C.; Mukherjee, S.; Rina, K. An assessment of groundwater salinization in Haryana state in India using hydrochemical tools in association with GIS. Environ. Earth Sci. 2017, 76, 465. [CrossRef] 36. Mahmoudi, N.; Nakhaei, M.; Porhemmat, J. Assessment of hydrogeochemistry and contamination of Varamin deep aquifer, Tehran Province, Iran. Environ. Earth Sci. 2017, 76, 370. [CrossRef] 37. Chang, J.; Wang, G. Major ions chemistry of groundwater in the arid region of Zhangye Basin, northwestern China. Environ. Earth Sci. 2010, 61, 539–547. [CrossRef] 38. Esteller, M.V.; Kondratenko, N.; Expósito, J.L.; Medina, M.; Del Campo, M.M. Hydrogeochemical characteristics of a volcanic-sedimentary aquifer with special emphasis on Fe and Mn content: A case study in Mexico. J. Geochem. Explor. 2017, 180, 113–126. [CrossRef] 39. Salem, Z.E.S.; Osman, O.M. Use of major ions to evaluate the hydrogeochemistry of groundwater influenced by reclamation and seawater intrusion, West Nile Delta, Egypt. Environ. Sci. Pollut. Res. 2017, 24, 3675–3704. [CrossRef] 40. Custodio, E.; Llamas, M. Hidrología Subterránea Volume 2, 1st ed.; Barcelona, O., Ed.; Omega: Barcelona, Spain, 1996. 41. Cuoco, E.; Verrengia, G.; De Francesco, S.; Tedesco, D. Hydrogeochemistry of Roccamonfina volcano (southern Italy). Environ. Earth Sci. 2010, 61, 525–538. [CrossRef] 42. Schoeller, H. Los Eaux Souterraines; Masson & Cie. Editeurs: París, France, 1962. 43. Kumar, S.K.; Bharani, R.; Magesh, N.S.; Godson, P.S.; Chandrasekar, N. Hydrogeochemistry and groundwater quality appraisal of part of south Chennai coastal aquifers, Tamil Nadu, India using WQI and fuzzy logic method. Appl. Water Sci. 2014, 4, 341–350. [CrossRef] 44. USEPA. National Recommended Water Quality Criteria; United States Environmental Protection Agency’, Office of Water, Office of Science and Technology. Available online: https://www.epa.gov/wqc (accessed on 9 February 2020). © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).